This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Autism Spectrum Disorder (ASD) is a severe neurodevelopmental disorder that affects an individual's ability to relate to other people, interpret social clues, and communicate. It is associated with repetitive behaviors and restricted interests. When all forms of the disorder are included, ASD affects up to 60 per 10,000 people. There is some evidence that the glutamate system may be abnormal in the brain and that the abnormalities may arise after early childhood. A non-invasive way of measuring glutamate in the brain is by using Magnetic Resonance Spectroscopy. This technique is based on the same principles as MRI but, instead of images, it provides high frequency spectra that allows the investigators to study the biochemical composition of the brain. In the proposed study, the investigators are primarily interested in studying glutamate concentrations in the brain of adolescents (12-17 years) with normal intelligence and autism. All adolescents enrolled will be offered a mock session in the scanner under the supervision of the clinical psychologist. If they tolerate this, they will have the actual scan. Patients can bring their favorite video to watch during the scanning procedure. In the analysis to follow the investigators will compare brain glutamate concentrations between children who have autism and typically developing children. Secondary analysis will involve measuring concentrations of other brain chemicals such as choline, creatine and NAA. Hypothesis: The goal of the study is to determine whether adolescents with autism exhibit increased glutamate concentrations (as estimated by the Glx peak at MRS) in the anterior cingluate, caudate, and limbic system compared to healthy volunteers matched for age and full IQ.